﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;
using System.Windows.Forms;

namespace CVS_log_visualiser
{
    class ListViewColumnSorter<T> : IComparer<T>, IComparer
    {
        /// <summary>
        /// Specifies the column to be sorted
        /// </summary>
        private int ColumnToSort;
        /// <summary>
        /// Specifies the order in which to sort (i.e. 'Ascending').
        /// </summary>
        private SortOrder OrderOfSort;
        /// <summary>
        /// Case insensitive comparer object
        /// </summary>
        private CaseInsensitiveComparer ObjectCompare;

        /// <summary>
        /// Class constructor.  Initializes various elements
        /// </summary>
        public ListViewColumnSorter()
        {
            // Initialize the column to '0'
            ColumnToSort = 0;

            // Initialize the sort order to 'none'
            OrderOfSort = SortOrder.None;

            // Initialize the CaseInsensitiveComparer object
            ObjectCompare = new CaseInsensitiveComparer();
        }

        /// <summary>
        /// This method is inherited from the IComparer interface.  It compares the two objects passed using a case insensitive comparison.
        /// </summary>
        /// <param name="x">First object to be compared</param>
        /// <param name="y">Second object to be compared</param>
        /// <returns>The result of the comparison. "0" if equal, negative if 'x' is less than 'y' and positive if 'x' is greater than 'y'</returns>
        public int Compare( object x, object y )
        {
            ListViewItem listviewX, listviewY;

            // Cast the objects to be compared to ListViewItem objects
            listviewX = (ListViewItem)x;
            listviewY = (ListViewItem)y;

            return Compare( listviewX.SubItems[ColumnToSort].Text, listviewY.SubItems[ColumnToSort].Text );
        }

        int Compare( string x, string y )
        {
            int compareResult;


            switch ( ColumnToSort )
            {
                case 1:
                    var subvers1 = x.Split( '.' );
                    var subvers2 = y.Split( '.' );

                    if ( subvers1.Length != 2 || subvers2.Length != 2 )
                        goto default;

                    int maj1 = int.Parse( subvers1[0] ), maj2 = int.Parse( subvers2[0] ), min1 = int.Parse( subvers1[1] ), min2 = int.Parse( subvers2[1] );

                    if ( maj1 != maj2 )
                        compareResult = maj1 < maj2 ? -1 : 1;
                    else
                        compareResult = min1 < min2 ? -1 : min1 == min2 ? 0 : 1;
                    break;

                case 2:
                    DateTime dtX, dtY;

                    if ( !DateTime.TryParse( x, out dtX ) || !DateTime.TryParse( y, out dtY ) )
                        goto default;

                    compareResult = DateTime.Compare( dtX, dtY );
                    break;
                default:
                    compareResult = ObjectCompare.Compare( x, y );
                    break;
            }

            // Calculate correct return value based on object comparison
            if ( OrderOfSort == SortOrder.Ascending )
            {
                // Ascending sort is selected, return normal result of compare operation
                return compareResult;
            }
            else if ( OrderOfSort == SortOrder.Descending )
            {
                // Descending sort is selected, return negative result of compare operation
                return ( -compareResult );
            }
            else
            {
                // Return '0' to indicate they are equal
                return 0;
            }
        }

        /// <summary>
        /// Gets or sets the number of the column to which to apply the sorting operation (Defaults to '0').
        /// </summary>
        public int SortColumn
        {
            set
            {
                ColumnToSort = value;
            }
            get
            {
                return ColumnToSort;
            }
        }

        /// <summary>
        /// Gets or sets the order of sorting to apply (for example, 'Ascending' or 'Descending').
        /// </summary>
        public SortOrder Order
        {
            set
            {
                OrderOfSort = value;
            }
            get
            {
                return OrderOfSort;
            }
        }

        public int Compare( T x, T y )
        {
            return Compare( x.ToString(), y.ToString() );
        }
    }
}
